Sanhedrin 5B

על שם חכמתו, דכתיב: ״אמר לחכמה אחתי את״.

It was due to his extraordinary wisdom, as it is written: “Say to wisdom: You are my sister” (Proverbs 7:4). Therefore, calling him: My sister’s son, was an indication of his great wisdom.

יתיר בכורות? אל יתיר. מאי טעמא? אילימא משום דלא חכים, הא קא אמרינן דחכים טובא! אלא משום דלא בקיע במומי.

The Talmud had related that R' Ḥiyya asked R' Yehuda HaNasi: May Rav declare a firstborn animal permitted, and that R' Yehuda HaNasi had responded: He may not declare such an animal permitted. The Talmud asks: What is the reason that he denied him this permission? If we say that it was because Rav was not sufficiently wise and learned, but that is difficult, as we already said that he was exceedingly wise. Rather, it must be that it was because, although he was quite knowledgeable about the halakha, he was not an expert with regard to blemishes, meaning that he lacked the practical expertise to apply the halakha to actual cases.

והאמר רב: שמונה עשר חדשים גדלתי אצל רועה בהמה, לידע איזה מום קבוע ואיזה מום עובר? אלא, לחלק לו כבוד לרבה בר חנה.

The Talmud rejects this answer. But didn’t Rav say: I apprenticed with a shepherd for 18 months in order to be able to know which blemish is a permanent blemish, and which is a temporary blemish? Evidently, he had a high level of practical expertise in this matter. The Talmud explains: Rather, it was in order to bestow honor upon Rabba bar Ḥana. R' Yehuda HaNasi wanted to ensure that Rabba bar Ḥana would be treated with respect, so he made sure that there was an area of halakha with regard to which the people would not be able to consult with Rav and would need to consult with Rabba bar Ḥana instead.